The timbers of Toona species are highly prized but now generally scarce through excessive logging activities throughout their distributional ranges. The genus is composed of only a few species, but phenotypic plasticity and genetic variation are responsible for much of the taxonomic complexity reflected in the literature. The species exhibit a phenomenal range of morphological variation, both within and between trees of the same population, and many of the features used by earlier authors to define their taxa have proved to be only slight morphological variants. Such vegetative characters include leaf and leaflet size; leaf and leaflet margin shape; indumentum type and trichome density. In particular, the velutinous pubescence, on which a number of Toona taxa have been based, occurs throughout the genus with the exception of T. sinensis, both inter- and infraspecifically, and even between seedlings of the same population. Both flowers and fruits are necessary for accurate identification of Toona species. This is especially relevant to T. sureni and T. ciliata, which are particularly difficult to differentiate in the herbarium.

About five species: E, S, and SE Asia, E Australia; four species (one endemic) in China.